Catalytic hydrogenation is a fundamental reaction in chemistry, and is used in a large number of chemical methods. Catalytic hydrogenation of ketones and aldehydes are useful and indispensable methods for the synthesis of alcohols, which are valuable end products and precursor chemicals in the pharmaceutical, agrochemical, flavor, fragrance, material and fine chemical industries.1 
The esters of 4-tert-butylcyclohexanol, and in particular, 4-tert-butylcyclohexyl acetate, are well known perfume ingredients. Cis-4-tert-butylcyclohexyl acetate is preferred in the perfume industry because of its intense woody odor with a flowery fragrance.2 Cis-4-tert-butylcyclohexyl acetate is obtained by acetylation of the corresponding alcohol. Various methods have been used in the industry to selectively produce cis-4-tert-butylcyclohexanol by hydrogenation of 4-tert-butylcyclohexanone. These include the use of iridium3 and rhodium4 catalysts or the use of bulky borohydride reagents, such as lithium trisamylborohydride.5 However, all of these methods suffer from significant drawbacks when applied on an industrial scale, for example, due to the low substrate catalyst ratios or the use of a very reactive reagent under stoichiometric conditions.
Noyori and co-workers developed hydrogenation conditions using the RuCl2(PR3)2(diamine) hydrogenation catalyst system.6 Noyori and co-workers also established a method for the production of cis-4-tert-butylcyclohexanol having 95-98% selectivity using the achiral catalyst RuCl2(PPh3)(en) and similar compounds.7 
Ruthenium aminophosphine complexes of the type RuCl2(aminophosphine)2 and RuCl2(diphosphine)(aminophosphine) have been previously reported for the hydrogenation of ketones, aldehydes and imines.8 